The Effect of the Grinding Time on the Mechanical Activation of MnO 2 Ore and Tea Plant Waste Carbonization Product

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1 Journal of Physical Science and Application 7 (4) (2017) doi: / / D DAVID PUBLISHING The Effect of the Grinding Time on the Mechanical Activation of MnO 2 Ore and Tea Plant Waste Carbonization Product Mustafa BOYRAZLI 1, Elif ARANCI ÖZTÜRK 1 and Yunus Emre BENKLİ 2 1. Department of Metallurgy and Materials Engineering, Faculty of Engineering, Fırat University, Elazığ 23119, Turkey 2. Department of Metallurgy and Materials Engineering, Faculty of Engineering, Atatürk University, Erzurum 25240, Turkey Abstract: In this study, pyrolusiteore (MnO 2 ) was subjected to mechanical milling with a high-energy mill with carbonized tea plant wastes and the effect of grinding time on the crystal structure of the material was investigated. The ratio of Mn/Fe was 8/1, the ratio of C/(MnO 2 + Fe 3 O 4 ) was 2 and the ratio of ball to ore was 10/1. The samples were mechanically ground at 10, 15, 20, 30, 60, 90 and 120 hours. In the processes performed on the attritor, the rotation speed of the mill shaft was determined to be 350 rpm. The results were characterized by TG-DTA, SEM and XRD analyzes. As a result of the experimental studies, it was observed that the samples subjected to mechanical grinding for 120 hours were gradually reduced due to the increasing grinding time at all the diffraction peaks when the XRD peaks were compared with the grinding times. In the thermogravimetric analysis, the sample milled for 120 hours, 50% weight loss was observed at 470 o C, weight loss of up to 56% was observed at progressive temperatures. Key words: Tea plant wastes, carbonization, mechanical grinding, pyrolusite ore. 1. Introduction The manganese is found to be the most commonly used metal after iron, aluminum and copper, with being the twelfth most frequently found element in the earth's crust. It is the most important of the alloy elements used in steel construction. And 90-95% of the manganese produced in the world is used as ferromanganese or silicomanganese in the iron-steel industry. Ferromanganese is added to the steel to prevent adverse effects of sulphate. In the production of abrasion resistant steel, however, it is necessary to use it as a manganese alloy element [1, 2]. Manganese ores have been processed for many years with the use of pyrometallurgical methods. Among these methods, the carbothermal reduction method is the most important industrial method known and intensively applied in the process of Corresponding author: Mustafa BOYRAZLI, Ph.D., assistant professor, research fields: iron and steel production, hydrometallurgical metal production, ore preparation, electrometallurgy. manganese ores. During this process, the reduction process develops very slowly and requires high temperatures [3]. In the first model, which is presented as Magma-Plasma Model in Mechanochemistry, large amounts of energy are emitted at the contact points of the particles that collide with each other. This energy is sufficient for the formation of a specific plasmatic state characterized by the emission of electrons and photons from the portions of the solid material that have gone up to an upper energy level. The surface of the contacted particles is highly irregular and the local temperatures can exceed 10,000 o C [4, 5]. The primary effect of mechanical activation on the mineral is disintegration. Thus, fresh, clean surfaces that have not been exposed to any effect before, resulting in semi-stable species [4, 5, 6]. (1) Vibrokinetic energy mill, (2) Planetary moving mills, (3) Centrifugal mills, (4) Eccentric vibratory mills, (5) Mixed ball mills and (6) Jet mills are used for the mechanical activation (Fig. 1) [7-13].

2 60 The Effect of the Grinding Time on the Mechanical Activation of MnO 2 Ore and The most importantt parameter in mechanical grinding is grinding time. The grinding time depends on the type of grinder used, the grinding speed, the ratio of the ball to the particle, and the grinding temperature [15]. If the temperature increase associated with the high diffusivity rate during milling of the metal particles in the mechanical grinding is too high, the resulting alloy will recrystallize and produce stable intermetallic phases. If the increase in temperature is small, amorphous or nanocrystalline structures are formed instead of recrystallization [15]. Mechanical activation by high-energy milling can ensure that chemical reactions that normally occur at higher temperatures occur even at room temperature. The mechanical activation process should be from 1 to 200 μm for the starting material dimensions [7, 15] ]. 2. Experimental Studies 2.1 Material and Method In this study, tea plant waste supplied fromrize-çaykur, carbonization product (Table 1), magnetite ore (Table 2) supplied from Elazığ region and manganese oxide ore (Table 3) supplied from Karaman region were used. The XRD analysess reveal that the ferrous manganese ore is in the form of pyrolusite (MnO 2 ) (Fig. 2). Manganese ore, magnetite ore and carbonized tea plant waste samples-125 to investigate the effect of mechanical milling on the crystal structure of material. And 250 μm in size were mixed at certain ratios gr of the mixture was weighed and placed in the attritor to perform mechanical milling. Mn/Fe, C/ /Mn, and ball/ore ratios of the mixtures in the attritor were taken as 8, 2 and 10, respectively. The samples were then subjected to mechanical milling for 10, 15, 20, 30, 60, 90 and 120 h. Stainless steel balls with a diameter of 8 mm and weighing approximately 2.04 gr/piece were used for this process. The mill shaft speed was determined at 350 rpm in the processes performed in the attritor and milling processes were carried out under dry milling conditions (Fig. 3) ). After the grinding, the XRD images of the samples weree recorded and their DTA/TG graphs were obtained. Fig. 1 Mill types used for mechanical activation, A-Balll Mill, B-Planetary Mill, C-Vibratory Mill, D-Mixed Balll Milll (Attritor), E-Shaft mill and F-Rolled milll [14]. Table 1 Carbonized tea plant waste analysis. Component C S Calorie Table 2 Analysiss of Elazığ-Keban region magnetite ore. Component Fe3O 3 4 SiO O 2 MnO 2 CaO Al2O 2 3 MgO Table 3 Analysiss of Karaman region manganese ore. Component MnO 2 Fe2O 2 3 SiO O 2 CaO Al2O 2 3 MgO BaO % ,,293 kal/gr % %

3 The Effect of the Grinding Time on the Mechanical Activation of MnO 2 Ore and 61 Fig. 2 XRD image of the used manganese ore. Fig. 3 Attritor mill used for mechanical grinding. irregularities, and that partial alloys were formed in the later stages of milling process. Mechanical milling increases dislocations in the structure, whichh leads to the formation of stress fields and deterioration in cage structures. These structuress showing shrinkage in X-ray diffraction peaks can be regarded as semi-stable amorphous phases. Compared to various minerals, mechanical activation of the pyrolusite mineral seems to require much longer times. Since both the pyrolusite and the magnetite mineral have Mohs hardness grades between 6 and 6.5, the amorphous state of this hard material requires longer times than the minerals with lower hardness grades [12]. 3.2 DTA-TG Analyzes 3. Experiment Results 3.1 XRD Analyzes Mechanical milled mixture samples were analyzed by XRD. Fig. 4 shows the XRD analysis of the mixture made at different grinding times. The comparison of the XRD peaks for different milling durations (Fig. 4) indicates that all diffraction peaks gradually decreased with an increase in milling duration. It is considered that the decrease in peak length was caused by the amorphous structure and mechanical energy transferred from structural The DTA-TG analyses of the mixture beforee grinding and after grinding are shown in Figs Both in the original mixture and in the milled sample, an endothermic reaction first took place, and after a certain temperature, it was determined that exothermic reactions occurred. On the sample subjected to mechanical activation for 120 hours, a symmetrical change similar to the Gaussian function was observed. It is inevitable thatt the mechanical grinding process will cause a large increase in surface areas of the particles. This increasee in surface area can be attributed to the material growing

4 62 The Effect of the Grinding Time on the Mechanical Activation of MnO 2 Ore and Fig. 4 XRD images of samples subjected to mechanical grinding at different times. Fig. 5 DTA-TG analysis of the un-grinding mixture.

5 The Effect of the Grinding Time on the Mechanical Activation of MnO 2 Ore and 63 Fig. 6 DTA-TG analysis of the mixture subjected to 10 hours milling. Fig. 7 DTA-TG analysis of the mixture subjected to 120 hours milling.

6 64 The Effect of the Grinding Time on the Mechanical Activation of MnO 2 Ore and Original sample Grinding for 10 hours Fig. 8 Comparison of TG graphs based on milling times. Grinding for 120 hours at much lower temperatures and the reduction in activation energy achieved by the reduction process. It is also possible to see in Fig. 8 that the change in the size of the grain forms a change on the thermogravimetric analysis. The thermogravimetric analyses show three different weight loss steps in the 10 h milling and four different weight loss steps in the 120 h milling. There was a 3% weight loss in the original sample up to 260 C. This may be due to surface moisture both on the surface and in the capillary channels. However, there was a 6% weight loss in the 120 h milled samples up to 245 C. At later temperature stages, there was a 51% weight loss in the original sample up to 730 o C, a 53% weight loss in the 10 h milled sample up to 540 o C, and a 50% and 56% weight loss in the 120 h milled sample up to 470 o C and at later temperatures, respectively. 4. Results In this study, pyrolusite ore (MnO 2 ) was subjected to mechanical milling with a high-energy mill with carbonized tea plant wastes and the effect of grinding time on the crystal structure of the material was investigated and the following general results were achieved. Mn/Fe, C/(MnO 2 +Fe 3 O 4 ) and ball/ore ratios of the mixture in the attritor were taken as 8, 2 and 10,

7 The Effect of the Grinding Time on the Mechanical Activation of MnO 2 Ore and 65 respectively and the mixture was subjected to mechanical grinding for periods ranging from 10 to 120 hours. The turning speed of the mill was determined to be 350 rpm and the milling was carried out in a dry environment. The TG-DTA and XRD analyzes of the obtained samples showed that the samples subjected to mechanical grinding for 120 hours gradually decreased with increasing grinding time at all the diffraction peaks when the XRD peaks were compared to the grinding times. It was observed a 6% weight loss in the 120 h milled samples up to 245 C. At later temperature stages, there was a 56% weight loss in the 120 h milled sample up to 470 C. References [1] Chatterjee, K. K Uses of Metals and Metallic Minerals. New Age Internatıonal (P) Limited, Publishers, 4835/24, Ansari Road, Daryaganj, New Delhi , ISBN (13) : , pp: [2] Alekseev, E. M., Elyutin, V. P., Levin, B. E. and Pavlov, Y. A FerroalaşımlarınİstihsaliElektrometalurji, Çev: Tulgar, E., sf , İ.T.Ü. Yayınları [3] Çardakli, İ. S Production of High Carbon Ferromanganese from a Manganese Ore Located in Erzincan. A Thesis Submitted to the Graduate School of Natural and Applied Sciences of Middle East Technical University, Ankara. [4] Göktaş, M Investigating the Effects of Intensive Milling on the Production of Synthetic Calcium Silicate from Marble Industry Wastes by Using Ceramic Materials. Ph.D. Thesis. Department of Mining Engineering, Institute of Natural and Applied Sciences, Inönü University. [5] Alp, A., Yıldız, K., Taşkın, E., Cebeci, A., and Aydın, S Investigation of the Effect of Mechanical Activation on Alumina Production from Diasporic Bauxite. TÜBİTAK MAG Project, No: 106M121, s: 129. [6] Welham, N. J Activation of the Carbothermic Reduction of Manganese Ore. Int. J. Miner. Process. 67: [7] Padden, S. A., and Reed, J. S Grindings Kinetics and Wear during Attrition Milling. Am. Cer. Soc. Bull. 77: [8] Gock, E., and Kurrer, K. E Increased Efficiency of the Vibratory Milling Process with the Eccentric Vibratory Mill. Aufbereitungs-Technik 39: [9] Gock, E., Vogt V., and Florescu, R Prototype of a New Centrifugal Tube Mill for Ultrafine Grinding. Aufbereitungs-Technik 42: [10] Mio, H., Kano, J., and Saito, F Scale-up Method of Planetary Ball Mill. Chem. Eng. Sei. 59: [11] Palaniandy, S., Azizli, K. A. M., Hussin, H., and Hashim, S. F. S Mechanochemistry of Silica on Jet Milling. J. Mater. Process Technol. 205: [12] Tunça, T., Apaydın, F., and Yıldız, K Effects of Mechanical Activation on the Structure of Nickeliferous Laterite. Proceedings of the 2nd International Congress APMAS [13] Mio, H., Kano, J., Saito, F., and Kaneko, K Effects of Rotational Direction and Rotation-to-Revolution Speed Ratio in Planetaiy Ball Milling. Mater. Sci. Eng. A332: [14] Murat Erdemoğlu, and Peter Baláž An Overview of Surface Analysis Techniques for Characterization of Mechanically Activated Minerals. Mineral Processing and Extractive Metallurgy Review 33 (1): [15] Suryanarayana, C Mechanical Alloying and Milling. Progress in Materials Science 46: